Weird Audio Issue

[ameristos]

lately, i've been getting this message when trying to start playing:

"problem detected with audio clock. check that your clock source and sample rate are correct."

i haven't changed any settings besides the input from presonus or eleven rack or pro tool aggregate depending on what i need to do at the time.

thing is, i can't seem to resolve this audio clock/clock source/sample rate error message until i restart pro tools.

to be honest, i am comfortable moving around pro tools with mixing, editing and recording, but rarely go into the settings. i create all my new songs from a template i made. i don't even know where the clock source settings are.

and... my sample rate never changes.

anyone have any idea what could be making this error message appear while trying to play? any suggestions how to fix it once it does pop up?

thanks.